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.TH UNLINK 2 "May 18, 2007"
.SH NAME
unlink, unlinkat \- remove directory entry
.SH SYNOPSIS
.LP
.nf
#include <unistd.h>

\fBint\fR \fBunlink\fR(\fBconst char *\fR\fIpath\fR);
.fi

.LP
.nf
\fBint\fR \fBunlinkat\fR(\fBint\fR \fIdirfd\fR, \fBconst char *\fR\fIpath\fR, \fBint\fR \fIflag\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBunlink()\fR function removes a link to a file. If \fIpath\fR names a
symbolic link, \fBunlink()\fR removes the symbolic link named by \fIpath\fR and
does not affect any file or directory named by the contents of the symbolic
link.  Otherwise, \fBunlink()\fR removes the link named by the pathname pointed
to by \fIpath\fR and decrements the link count of the file referenced by the
link.
.sp
.LP
The \fBunlinkat()\fR function also removes a link to a file. See
\fBfsattr\fR(7). If the \fIflag\fR argument is 0, the behavior of
\fBunlinkat()\fR is the same as \fBunlink()\fR except in the processing of its
\fIpath\fR argument. If \fIpath\fR is absolute, \fBunlinkat()\fR behaves the
same as \fBunlink()\fR and the \fIdirfd\fR argument is unused. If \fIpath\fR is
relative and \fIdirfd\fR has the value \fBAT_FDCWD\fR, defined in
<\fBfcntl.h\fR>, \fBunlinkat()\fR also behaves the same as \fBunlink()\fR.
Otherwise, \fIpath\fR is resolved relative to the directory referenced by the
\fIdirfd\fR argument.
.sp
.LP
If the \fIflag\fR argument is set to the value \fBAT_REMOVEDIR\fR, defined in
<\fBfcntl.h\fR>, \fBunlinkat()\fR behaves the same as \fBrmdir\fR(2) except in
the processing of the \fIpath\fR argument as described above.
.sp
.LP
When the file's link count becomes 0 and no process has the file open, the
space occupied by the file will be freed and the file is no longer accessible.
If one or more processes have the file open when the last link is removed, the
link is removed before \fBunlink()\fR or \fBunlinkat()\fR returns, but the
removal of the file contents is postponed until all references to the file are
closed.
.sp
.LP
If the \fIpath\fR argument is a directory and the filesystem supports
\fBunlink()\fR and \fBunlinkat()\fR on directories, the directory is unlinked
from its parent with no cleanup being performed.  In UFS, the disconnected
directory will be found the next time the filesystem is checked with
\fBfsck\fR(8). The \fBunlink()\fR and \fBunlinkat()\fR functions will not fail
simply because a directory is not empty. The user with appropriate privileges
can orphan a non-empty directory without generating an error message.
.sp
.LP
If the \fIpath\fR argument is a directory and the filesystem does not support
\fBunlink()\fR and \fBunlink()\fR on directories (for example, ZFS), the call
will fail with \fBerrno\fR set to \fBEPERM\fR.
.sp
.LP
Upon successful completion, \fBunlink()\fR and \fBunlinkat()\fR will mark for
update the \fBst_ctime\fR and \fBst_mtime\fR fields of the parent directory.
If the file's link count is not 0, the \fBst_ctime\fR field of the file will be
marked for update.
.SH RETURN VALUES
.sp
.LP
Upon successful completion, \fB0\fR is returned.  Otherwise, \fB\(mi1\fR is
returned, \fBerrno\fR is set to indicate the error, and the file is not
unlinked.
.SH ERRORS
.sp
.LP
The \fBunlink()\fR and \fBunlinkat()\fR functions will fail if:
.sp
.ne 2
.na
\fB\fBEACCES\fR\fR
.ad
.RS 16n
Search permission is denied for a component of the \fIpath\fR prefix, or write
permission is denied on the directory containing the link to be removed.
.RE

.sp
.ne 2
.na
\fB\fBEACCES\fR\fR
.ad
.RS 16n
The parent directory has the sticky bit set and the file is not writable by the
user, the user does not own the parent directory, the user does not own the
file, and the user is not a privileged user.
.RE

.sp
.ne 2
.na
\fB\fBEBUSY\fR\fR
.ad
.RS 16n
The entry to be unlinked is the mount point for a mounted file system.
.RE

.sp
.ne 2
.na
\fB\fBEFAULT\fR\fR
.ad
.RS 16n
The \fIpath\fR argument points to an illegal address.
.RE

.sp
.ne 2
.na
\fB\fBEILSEQ\fR\fR
.ad
.RS 16n
The path argument includes non-UTF8 characters and the file system accepts only
file names where all characters are part of the UTF-8 character codeset.
.RE

.sp
.ne 2
.na
\fB\fBEINTR\fR\fR
.ad
.RS 16n
A signal was caught during the execution of the \fBunlink()\fR function.
.RE

.sp
.ne 2
.na
\fB\fBELOOP\fR\fR
.ad
.RS 16n
Too many symbolic links were encountered in translating \fIpath\fR.
.RE

.sp
.ne 2
.na
\fB\fBENAMETOOLONG\fR\fR
.ad
.RS 16n
The length of the \fIpath\fR argument exceeds \fBPATH_MAX\fR, or the length of
a \fIpath\fR component exceeds \fBNAME_MAX\fR while \fB_POSIX_NO_TRUNC\fR is in
effect.
.RE

.sp
.ne 2
.na
\fB\fBENOENT\fR\fR
.ad
.RS 16n
The named file does not exist or is a null pathname.
.RE

.sp
.ne 2
.na
\fB\fBENOLINK\fR\fR
.ad
.RS 16n
The \fIpath\fR argument points to a remote machine and the link to that machine
is no longer active.
.RE

.sp
.ne 2
.na
\fB\fBENOTDIR\fR\fR
.ad
.RS 16n
A component of the \fIpath\fR prefix is not a directory or the provided
directory descriptor for \fBunlinkat()\fR is not \fBAT_FDCWD\fR or does not
reference a directory.
.RE

.sp
.ne 2
.na
\fB\fBEPERM\fR\fR
.ad
.RS 16n
The named file is a directory and {\fBPRIV_SYS_LINKDIR\fR} is not asserted in
the effective set of the calling process, or the filesystem implementation does
not support \fBunlink()\fR or \fBunlinkat()\fR on directories.
.RE

.sp
.ne 2
.na
\fB\fBEROFS\fR\fR
.ad
.RS 16n
The directory entry to be unlinked is part of a read-only file system.
.RE

.sp
.LP
The \fBunlink()\fR and \fBunlinkat()\fR functions may fail if:
.sp
.ne 2
.na
\fB\fBENAMETOOLONG\fR\fR
.ad
.RS 16n
Pathname resolution of a symbolic link produced an intermediate result whose
length exceeds {\fBPATH_MAX\fR}.
.RE

.sp
.ne 2
.na
\fB\fBETXTBSY\fR\fR
.ad
.RS 16n
The entry to be unlinked is the last directory entry to a pure procedure
(shared text) file that is being executed.
.RE

.SH USAGE
.sp
.LP
Applications should use \fBrmdir\fR(2) to remove a directory.
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	T{
\fBunlink()\fR is Standard; \fBunlinkat()\fR is Evolving
T}
_
MT-Level	Async-Signal-Safe
.TE

.SH SEE ALSO
.sp
.LP
.BR rm (1),
.BR close (2),
.BR link (2),
.BR open (2),
.BR rmdir (2),
.BR remove (3C),
.BR attributes (7),
.BR fsattr (7),
.BR privileges (7)
